Field of the Disclosure
The present invention relates generally to power converters, and more specifically controllers that can detect an input and output of a power converter from a single pin.
Background
Electronic devices use power to operate. Switched mode power converters are commonly used due to their high efficiency, small size and low weight to power many of today's electronics. Conventional wall sockets provide a high voltage alternating current. In a switch mode power converter, a high voltage alternating current (ac) input is converted to provide a well-regulated direct current (dc) output through an energy transfer element. The switched mode power converter control circuit usually provides output regulation by sensing one or more inputs representative of one or more output quantities and controlling the output in a closed loop. In operation, a switch is utilized to provide the desired output by varying the duty cycle (typically the ratio of the on time of the switch to the total switching period), varying the switching frequency, or varying the number of pulses per unit time of the switch in a switched mode power converter.
Power converters are occasionally exposed to surges in the received input voltage, which is generally referred to as an overvoltage condition. Input and output overvoltages can be dangerous in power supplies: input voltages going too high may cause high voltage (HV) switches to fail due to high voltage and high current conditions occurring at the same time, with the switch failing even below its breakdown voltage. Excessive output voltage may cause electrical overstress on the output capacitors, electrolytic in most cases, which may cause it to fail causing fire or other hazards. Furthermore, light emitting diode (LED) bulb manufacturers sometimes perform production tests with the LED load disconnected. In this situation, the bulb (with its driver circuitry) should survive and not degrade lifetime expectations. In this case, it's crucial to minimize stress on output electrolytic capacitor.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.